Polybutylene terephthalate resin composition for molded body for welding polyester elastomer, and composite molded body

Abstract

A polybutylene terephthalate resin composition for bonding a polyester elastomer for use in a molded article for welding a polyester elastomer that enables bonding by insert molding; and that ensures a practical bonding strength, even in a portion where stress is generated. The polybutylene terephthalate resin composition comprises: 40 to 95 mass % of a polybutylene terephthalate resin (A); 4 to 40 mass % of a polyester block copolymer (B); 0 to 50 mass % of a copolyester resin (C) different from (B); and 0 to 55 mass % of an inorganic filler (D), the polyester block copolymer (B) comprising, as a constituent, a hard segment composed of a polyester having a specific structure.

The invention claimed is: 
     
       1. A polybutylene terephthalate resin composition for use in a molded article for welding a polyester elastomer, the polybutylene terephthalate resin composition comprising: 40 to 95 mass % of a polybutylene terephthalate resin (A); 4 to 40 mass % of a polyester block copolymer (B); >0 to 50 mass % of a copolyester resin (C) different from (B); and 0 to 55 mass % of an inorganic filler (D), the polyester block copolymer (B) comprising, as constituents, a hard segment (a3) and a soft segment (a4), the hard segment (a3) being composed of a polyester containing, as dicarboxylic acid components, terephthalic acid or an ester-forming derivative thereof (a1) and at least one dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof (a2) at a molar ratio ((a1)/(a2)) of 1 to 4, and the soft segment (a4) being at least one member selected from aliphatic polyethers, aliphatic polyesters and aliphatic polycarbonates. 
     
     
       2. The polybutylene terephthalate resin composition according to  claim 1 , wherein the copolyester resin (C) is a polyester resin comprising an ethylene terephthalate unit or a butylene terephthalate unit copolymerized with at least one of alkyl side chain-containing glycol and isophthalic acid. 
     
     
       3. A composite molded article in which a molded article comprising a polybutylene terephthalate resin composition and a polyester elastomer are welded, wherein the polybutylene terephthalate resin composition comprises: 40 to 95 mass % of a polybutylene terephthalate resin (A); 4 to 40 mass % of a polyester block copolymer (B); 0 to 50 mass % of a copolyester resin (C) different from (B); and 0 to 55 mass % of an inorganic filler (D), the polyester block copolymer (B) comprising, as constituents, a hard segment (a3) and a soft segment (a4), the hard segment (a3) being composed of a polyester containing, as dicarboxylic acid components, terephthalic acid or an ester-forming derivative thereof (a1) and at least one dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof (a2) at a molar ratio ((a1)/(a2)) of 1 to 4, and the soft segment (a4) being at least one member selected from aliphatic polyethers, aliphatic polyesters and aliphatic polycarbonates. 
     
     
       4. The composite molded article according to  claim 3 , wherein the copolyester resin (C) is a polyester resin comprising an ethylene terephthalate unit or a butylene terephthalate unit copolymerized with at least one of alkyl side chain-containing glycol and isophthalic acid. 
     
     
       5. A method for producing a composite molded article, comprising placing a molded article comprising a polybutylene terephthalate resin composition as an insert material in a mold, and welding a polyester elastomer by injection molding, wherein the polybutylene terephthalate resin composition comprises: 40 to 95 mass % of a polybutylene terephthalate resin (A); 4 to 40 mass % of a polyester block copolymer (B); 0 to 50 mass % of a copolyester resin (C) different from (B); and 0 to 55 mass % of an inorganic filler (D), the polyester block copolymer (B) comprising, as constituents, a hard segment (a3) and a soft segment (a4), the hard segment (a3) being composed of a polyester containing, as dicarboxylic acid components, terephthalic acid or an ester-forming derivative thereof (a1) and at least one dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof (a2) at a molar ratio ((a1)/(a2)) of 1 to 4, and the soft segment (a4) being at least one member selected from aliphatic polyethers, aliphatic polyesters and aliphatic polycarbonates. 
     
     
       6. The method for producing a composite molded article according to  claim 5 , wherein the copolyester resin (C) is a polyester resin comprising an ethylene terephthalate unit or a butylene terephthalate unit copolymerized with at least one of alkyl side chain-containing glycol and isophthalic acid.